The rare and flawless Blue Moon Diamond sold for 48.6m Swiss francs (Â£31.9m, $48.4 million) to a Hong Kong buyer on Wednesday (11 November), setting a world record for a gemstone at auction, Sothebys said. The cushion-shaped diamond, mounted on a ring, has the top grading of fancy vivid blue and weighs 12.03 carats. It had a pre-sale estimate of $35-55m. The previous record was held by the Graff Pink of 24.78 carats, sold by Sothebys for $46.2m in November 2010.Nov 12, 2015